Intrathoracic gastric volvulus is a rare event. It occurs when the stomach undergoes organoaxial torsion in the chest, caused either by concomitant enlargement of the hiatus or by a diaphragmatic hernia. A delay in diagnosis and treatment can result in fatal complications such as gastric ischemia, perforation, and hemorrhage. We report a case of intrathoracic localization of an acute and incarcerated organoaxial gastric volvulus caused by a left-sided diaphragmatic hernia resulting from a diaphragmatic injury. The patient had undergone a left splenopancreatectomy 4 years earlier for non-Hodgkin's lymphoma. We performed an emergency left thoracotomy with reduction of the acute volvulus, resection of the adhesions, and exeresis of an inflammatory mass from the omentum, with good results. The mechanisms of volvulus and diaphragmatic hernia with the relative diagnostic and therapeutic implications are discussed after this case report.